1. Field of the Invention
The present invention relates to a keypad and a method for manufacturing the same, and in particular to a keypad having three-dimensional patterns and a method for manufacturing the same.
2. Description of Prior Art
With the progress and development of technology, modern consumers request electronic products such as mobile phone, personal digital assistant (PDA), ultra mobile personal computer (UMPC) to be designed in a more personalized and delicate manner. However, these electronic products can be only operated via keypad so as to transmit signals from a user to the electronic products or vice versa. Moreover, the user requests the keypad of the electronic product to be varied continuously. Therefore, it is an important issue for the manufacturers of keypad to develop keypad of more competitiveness to satisfy the request of modern people.
Japanese Patent Publication No. 2000-340059 discloses a conventional keypad and a method for manufacturing the same. As shown in FIG. 1, the keypad includes a base layer 10a, a pattern layer 12a, a keycap layer 14a and a colored light-transmitting film 17a. The front surface of the pattern layer 12a is provided with three-dimensional patterns 121a. The keycap layer 14a is provided with troughs to correspond to the three-dimensional patterns 121a and the keycap layer 14a is overlapped on the front surface of the pattern layer 12a. The back surface of the pattern layer 12a is printed with the colored light-transmitting film 17a. The base layer 10a is adhered to the underside of the light-transmitting film 17a. With the above arrangement, a keypad can be achieved. Further, the method for manufacturing the keypad includes a step of overlapping a pattern layer and a keycap layer. First, a bottom plate and three-dimensional patterns are integrally formed. The three-dimensional patterns protrude from the top surface of the bottom plate. Next, the top surface of the three-dimensional pattern is printed. Then, the three-dimensional patterns of the bottom plate are embedded in the keycap layer via a hot welding process.
Further, Japanese Patent publication No. 2000-331554 discloses another kind of keypad and a method for manufacturing the same. According to this method for manufacturing the keypad, cavities having three-dimensional patterns are formed in an inner surface of a keycap layer. The inner surface of the keycap layer is printed with a light-shielding film. Then, the inner surface of the cavity having three-dimensional patterns is coated with a light-transmitting colored film. In this way, the method for manufacturing keypad can be completed.
Although the above-mentioned keypad and the method for manufacturing the same can obtain keypads having three-dimensional patterns, Patent Publication No. 2000-340059 only teaches a step of printing on the top surface of the three-dimensional patterns. Therefore, the whole shape of the three-dimensional pattern cannot be displayed sufficiently, and thus the recognition and aesthetic feeling thereof are not good. Further, since both the above-mentioned patent publications do not provide a light-guiding plate, the illuminated area is relatively small and thus it can be only applied to a relative small keypad or single keypad. Therefore, for a keypad having a large operating area, the conventional keypad cannot satisfy this requirement for use.
Further, China Patent Publication No. CN2544299Y discloses another keypad assembly, which includes a keypad layer, a first pattern layer, a refracting layer and a second pattern layer. The keypad layer is a light-transmitting body. The first pattern layer is an opaque body that is overlapped with the keypad layer. The first pattern layer is provided with first patterns formed by hollowed portions. The refracting layer is a translucent body that is located below the keypad layer and the first pattern layer. The underside of the refracting layer is formed with a back surface. The second pattern layer is an opaque body that is attached to the back surface of the refracting layer. The second pattern layer is provided with second patterns formed by hollowed portions. The light emitted by light-emitting elements is projected toward the keypad layer from the underside of the second pattern layer, so that the first and second patterns can be displayed on the keypad layer, thereby achieving a multiple displaying effect. Although the above-mentioned keypad assembly has a multiple displaying effect, it relies on the fact that the first and second patterns are formed on the first and second pattern layers respectively. As a result, the total thickness of the keypad would be large and thus increasing the weight thereof. Therefore, it is not suitable for the electronic products that tend to be produced toward more and more compact. Further, the light-emitting element is formed underneath the second pattern layer, increasing the total height. As a result, the thickness of the electronic product cannot be reduced sufficiently. Moreover, the refracting layer is a translucent body, so that the recognition and aesthetic feeling of the displayed second pattern are not good.